Isotherm 2555 Compact Classic Water Cooled Refrigeration Component System

[crazyoldboatguy]

Greetings, Has anyone ever used this type of refrigeration unit? It comes with a self pumping water cooling unit that utilizes a thru hull gray water drain as the heat sink (no pun intended). Certainly less expensive than a keel cooler and has less moving parts that a pump run water cooled unit. I just wonder about how efficient it is and also am concerned about fouling and the resultant cleaning. Since the heat exchanger is up in the drain, I wonder how you get to it to clean it?

With all these concerns I may just go with the keel cooler but would appreciate any input.

[model 10]

We have no trouble with ours. I have the zink attached and there is no loss. I think the stuff you dump down the drain might keep it clean. From listening to others, it's hard to tell if it runs less and I have no way to measure it. We don't keep frozen stuff and have it turned all the way down and still the beer and wine are perfect.

[crazyoldboatguy]

How big is your box? Is it a custom built-in or an off the shelf box? How much insulation? If your location is accurate, you are in a fairly warm place so that would compare to where I will likely be going. Thanks for your comment. Very helpful.

[Terra Nova]

That Isotherm is pretty good but is limited by the sink-drain-cooler. OK if you're just trying to keep beer and soda cool. Much better is the Frigoboat keel-cooled unit. I've installed several. They will freeze your freezer and are dead quiet. Reports are 1 amp/hour for a well insulated box in socal. Both are simple to install.

[model 10]

Originally Posted by crazyoldboatguy

How big is your box? Is it a custom built-in or an off the shelf box? How much insulation? If your location is accurate, you are in a fairly warm place so that would compare to where I will likely be going. Thanks for your comment. Very helpful.

The water temp is probably mid to high 80's. Our box is maybe 6.5 cu' with 3" insulation on sides and top but the bottom is much thinner. When on the hard in a boat yard, ice does not last that long.

[Terra Nova]

Your box is insufficiently insulated.

[model 10]

Originally Posted by Terra Nova

Your box is insufficiently insulated.

I don't see an easy solution to that. If I knew more about the duty cycles of the refer unit I would have a better idea how bad the insulation is. All I do know is that on a very low setting, it's just above freezing inside and the compressor comes on every 15-20 min and runs for 5 min or so while in a quiet anchorage.

[crazyoldboatguy]

I plan on having 2 separate boxes with separate compressors. Both will be set up to be either fridges or freezers. Not sure of the capacity since I have not laid out the accommodations yet but they will be 3 cu ft minimum. I will be insulating both units, which will be side to side as tho they will be freezers - 6" equivalent all around. I will supplement the foam insulation w/aerogel so as to reduce the space required and the cost. I had looked into vacuum panels but their fragility and longevity issues put me off.

I really liked the drain/cooler concept but also feared the demands that my set up will make doesn't work with that set up. I will be off grid for long periods of time relying on solar/wind/water generation systems and will not have a internal combustion generator.

I see using a freezer more often that a fridge - can use the freezer to make ice for a cooler if I have need for that. I like the flexibility. But it appears I may have to opt for the keel cooler - I like the fact that no pump is needed as opposed to a water cooled set up. Efficiency is most important if I am to succeed in having a true freezer.

Thanks for the comments.

[model 10]

I hope I did not imply that we could not freeze stuff with our unit. We can easily it's just we have no need to. Frozen beer is no good.

[crazyoldboatguy]

The down side of not having enough insulation isn't necessarily that you can't freeze the beer, but rather, at what cost. The increased energy consumption with 3" of insulation (and less at the bottom) means more amperage used as well as condensation that forms on the outside of the insulation as the warm moist air hits the cooler fridge. You may not even see this condensation as it may collect inside the outer covering, drip down to the cabin sole and cause some serious damage. For me, on a wooden boat, this is a serious no no.

If you're happy with your system and it isn't causing a problem, sit back and enjoy the beer.

[Triumphant]

I am not sure that the idea that fridges have to be water-cooled in the Tropics still apply

In Belize, The Mooring and Sunsail fleets now have very few water cooled fridges left, the new boats are all air cooled as the compressors are so much better

I still have a water cooled Isotherm but if, for any reason the water flow is restricted, the newer Danfoss compressor will run for a long long time, the old Isotherm one would pack up within minutes

So bottom line, although I live in the tropics, I would not fit another water cooled fridge

[crazyoldboatguy]

I am concerned about where the heat goes while you are cooling off the compressor. With a fan based system, you need space around the unit. Placement becomes more crucial. You are pumping heat into the hull in a hot climate. Into my living space.

I have no experience in this area so don't know if the amount of heat blown into the hull with a properly insulated freezer is a major problem or a minor one.

I see that water cooled can mean a few different things. As far as having a water pump bring water on board to cool the compressor - I think that would be the least advantageous due to the need for a separate pump. The keel cooler doesn't require that extra pump - neither does the system that uses a heat exchanger in the sink drain thru hull.

I am not sure I would make a decision about my refrigeration needs based on what charters companies do. Folks don't live on those boats for a long time - even the owners are there for short periods, otherwise they wouldn't be chartering the vessel. What do these charter boats use for auxiliary power? If they rely on a generator, then the increased power demands due to a less efficient system aren't that much of a problem. I will not have a generator on board as a major part of my charging system.

Thanks again for the comments. Very helpful

[SV THIRD DAY]

Originally Posted by Triumphant

I am not sure that the idea that fridges have to be water-cooled in the Tropics still apply

They don't. Technautics has been building Air Cooled refrigeration units for cruiser bound for the tropics longer than I have been alive, since 1968. Ice cream and Cold beer in the tropics without the drama of using evil sea water for cooling.

In additional to cruisers and off the grid folks a big client for us is the US Military for their solar portable food service units. They are entirely air cooled and designed for ambient temps of 135-degs. Inside the box mechanical room (the door you see) is the same air cooled condensing/compressor unit we sell to cruisers.

[crazyoldboatguy]

Still not addressed is the effect on the temp in the hull from running an air cooled compressor. I don't think the Navy is too worried about the overall efficiency of their refrigeration units in the same manner I am. They don't use solar panels and a wind generator to top off their batteries. They have capacity to refuel in the middle of nowhere much easier than I do. It is a poor comparison.

If I am removing heat from the freezer - where is the heat going? If the compressor is fan cooled, the heat is going into my hull. If my hull is already hot, adding more heat to it seems counterproductive, unless I like that much heat. In which case - why do I have a freezer?

I would not bring seawater into my boat to cool the compressor. The keel cooler would do that outside of the boat. Where the heat will be sent.

[SV THIRD DAY]

Originally Posted by crazyoldboatguy

Still not addressed is the effect on the temp in the hull from running an air cooled compressor. I don't think the Navy is too worried about the overall efficiency of their refrigeration units in the same manner I am. They don't use solar panels and a wind generator to top off their batteries. They have capacity to refuel in the middle of nowhere much easier than I do. It is a poor comparison.

If I am removing heat from the freezer - where is the heat going? If the compressor is fan cooled, the heat is going into my hull. If my hull is already hot, adding more heat to it seems counterproductive, unless I like that much heat. In which case - why do I have a freezer?

I would not bring seawater into my boat to cool the compressor. The keel cooler would do that outside of the boat. Where the heat will be sent.

The unit in the photo was built to run completely off of solar in 135-degs temps...so energy efficiency is a HUGE issue which is why I thought it was a good comparison. Technautics won the bid by having the most energy efficient unit that was tested. What does energy efficient mean for a cruiser that doesn't want a 6ft x 6ft cube? 25AH/day for a 7cf box with 4" of insulation...that's as good as it gets and without the sea water corrosion zinc drama.

Where does the heat go...into a Laz or engine compartment or vented. After spending summers in the Sea of Cortez on the hook, I didn't even notice the heat from the air cooled refrigeration that was mounted in the engine compartment to be honest. It's one of those issues thrown around as a worry but in pratice not a big deal if you can mount the unit outside of the living cabin. I wouldnt want the warm air blowing on my head in the bunk or on my feet at the salon but that's just about installation planning.

There's also a little confusion here that there is an air duct blowing air out into the cabin, that's not correct. The small 12v fan pulls air through the condenser and then on the compressors electronic module, but there is no need to duct the air out of the laz or engine room. As long as the space will not be heat soaked to 125-degs, then you don't need to vent out the warm air...125-degs is HOT so most clients don't bother venting the locker and then don't have hot air blowing into the cabin space.